Exhaust filter system for non-road engine

ABSTRACT

An exhaust filter system, adapted for removing substances entrained in an exhaust gas from a nonroad engine, includes a casing having a filter cavity for communicating with an exhaust outlet of the generator and a filter core which includes a plurality of filtering loops, each having a plurality of air pores, coaxially received in the filter cavity, a plurality of filtering spacers each having a plurality of air meshes and positioned between each two filtering loops to define a plurality of air passages therebetween, and a catalyzing element for chemically reacting with the substances of the exhaust gas. Therefore, when the exhaust gas passes through the air passages of the filter core, the exhaust gas is evenly diffused to the filter cavity through the air pores and the air meshes so as to enhance a chemical reaction of the exhaust gas with the catalyzing element.

CROSS REFERENCE OF RELATED APPLICATION

This is a divisional application that claims the benefit of priorityunder 35 U.S.C. §119 to a non-provisional application, application Ser.No. 10/976,713, filed Oct. 28, 2004, which is a divisional applicationof a non-provisional application, application Ser. No. 10/392,524, filedMar. 19, 2003.

BACKGROUND OF THE PRESENT INVENTION

1. Field of Invention

The present invention relates to a nonroad engine, and more particularlyto an exhaust filter system for a diesel/gasoline nonroad engine forsuch as a generator, which substantially removes harmful substances ofexhaust gases from the generator.

2. Description of Related Arts

Conventional generator generally includes a nonroad internal combustionengine comprising a crankshaft, and a fuel reservoir for supplying fuelto the internal combustion engine in such a manner that when the fuel isignited in the internal combustion engine to complete a combustionprocess, the crankshaft is driven to rotate for producing mechanicalpower. Therefore, by incorporating an induction rotor with the internalcombustion engine, the mechanical rotational force produced by theinternal combustion engine is transformed into a motional electromotiveforce through a magnetic force provided by the induction rotor so as toconvert into an electrical energy.

Generally speaking, there are two types of nonroad engine, which arediesel engine and gasoline engine, commonly used. Since the compressionratio of the diesel engine is higher than that of the gasoline engine,the diesel engine is usually more efficient than the gasoline engine.However, both diesel and gasoline engines have a common drawback.

Due to the inefficiency of fuel ignition in the nonroad engine, theresulting incomplete combustion of the fuel, especially for the dieselengine, leads to carbon monoxide (CO), nitrogen oxides (NOx) andunburned hydrocarbons (HC) in the exhaust gas that contributes to airpollution. Therefore, in order to market the nonroad engines andgenerators in the United States, the exhaust gas of the nonroad enginemust meet the exhaust certification standard (STD) and certificationlevels (CERT) for hydrocarbon (HC), oxides of nitrogen (NOx), ornon-methane hydrocarbon plus oxides of nitrogen (NMHC═NOx), carbonmonoxide (CO, and particular matter (PM) in grams per kilowatt-hour(g/kW-hr), and the opacity-of-smoke certification standards andcertification levels in percent (%) during acceleration (Accel), lugging(Lug), and the peak value from either mode (Peak) for this engine family(Title 13, California Code of Regulations, (13 CCR) Section 2423) of theUnited States Environmental Protection Agency and the state agency suchas California Air Resources Board.

SUMMARY OF THE PRESENT INVENTION

An object of the present invention is to provide an exhaust filtersystem for a nonroad engine which can substantially remove harmfulsubstances of exhaust gas from the nonroad engine

Another object of the present invention is to provide an exhaust filtersystem for a nonroad engine (19.5 KW of less) for generator whichexhaust gas meets the exhaust certification standard (STD) andcertification levels (CERT) for hydrocarbon (HC), oxides of nitrogen(NOx), or non-methane hydrocarbon plus oxides of nitrogen (NMHC═NOx),carbon monoxide (CO, and particular matter (PM) in grams perkilowatt-hour (g/kW-hr), and the opacity-of-smoke certificationstandards and certification levels in percent (%) during acceleration(Accel), lugging (Lug), and the peak value from either mode (Peak) forthis engine family (Title 13, California Code of Regulations, (13 CCR)Section 2423) of the United States Environmental Protection Agency.

Another object of the present invention is to provide an exhaust filtersystem which is specifically designed for a nonroad engine having nomore than 25 horsepower. In other words, the exhaust filter system isadapted to employ with a portable generator or a lawn mower to minimizeair pollution.

Another object of the present invention is to provide an exhaust filtersystem for a generator, wherein the exhaust filter system can beincorporated with a diesel engine or a gasoline engine of the generatorto effectively filter out the harmful substances of the exhaust gas fromthe generator.

Another object of the present invention is to provide an exhaust filtersystem for a generator, wherein a filter core comprises a flat filteringnet and a corrugated filtering layer overlapped thereto to form aplurality of air passages between the flat and corrugated filteringlayers in such a maimer that when the exhaust gas passes through the airpassages, the exhaust gas is evenly diffused to the filter core tochemically react with a catalyzing element. Therefore, the harmfulsubstances in the exhaust gas can be substantially filtered out.

Another object of the present invention is to provide an exhaust filtersystem for a generator, wherein the exhaust gas is evenly distributedthough the filter core for maximizing a contacting area between theexhaust gas and the filter core so as to enhance the catalyzing processof the exhaust gas.

Another object of the present invention is to provide an exhaust filtersystem for a generator, wherein the manufacturing process of the filtercore is simply by coiling a flat filtering layer with a corrugatedfiltering layer, so as to minimize the manufacturing cost of the exhaustfilter system of the present invention.

Another object of the present invention is to provide an exhaust filtersystem for a generator, which successfully provides an economic andefficient solution for filtering the harmful substances of exhaust gasfrom the generator, so as to minimize air pollution contributed by thegenerator.

Accordingly, in order to accomplish the above objects, the presentinvention provides an exhaust filter system for removing substancesentrained in an exhaust gas from a nonroad engine, having a horsepowernot more than 25 hp, having an exhaust outlet to discharge the exhaustgas, comprising:

a filter casing having an intake opening for communicating with theexhaust outlet, a discharging opening, and a filter cavity communicatingthe intake opening with the discharging opening for guiding the exhaustgas to flow from the intake opening to the discharging opening throughthe filter cavity; and

a filter core, which is disposed in the filter cavity, comprising:

a plurality of tubular filtering loops coaxially received in the filtercavity, wherein a plurality of air pores are formed on the filteringloops for allowing the exhaust gas passing therethrough;

a plurality of tubular filtering spacers each positioned between eachtwo filtering loops to define a plurality of axial air passages betweenthe filtering spacers and the filtering loops so as to communicate withthe air pores thereof, wherein a plurality of air meshes are formed onthe filtering spacers to communicate with the air passages; and

a catalyzing element provided on the filtering loops and the filteringspacers for chemically reacting with the substances of the exhaust gas,thereby, when the exhaust gas passes through the air passages of thefilter core, the exhaust gas is evenly diffused to the filter cavitythrough the air pores and the air meshes so as to enhance a chemicalreaction of the exhaust gas with the catalyzing element.

These and other objectives, features, and advantages of the presentinvention will become apparent from the following detailed description,the accompanying drawings, and the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of an exhaust filter system for a generatoraccording to a preferred embodiment of the present invention.

FIG. 2 is a partially front sectional view of the exhaust filter systemaccording to the above preferred embodiment of the present invention.

FIG. 3 is a sectional view of the filter core of the exhaust filtersystem according to the above preferred embodiment of the presentinvention.

FIG. 4 is a perspective view of a filter core of the exhaust filtersystem according to the above preferred embodiment of the presentinvention, illustrating the corrugated filtering layer being overlappedon the flat filtering layer to form the air filtering net.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring to FIG. 1 of the drawings, the present invention provides anexhaust filter system 2 for nonroad engine. According to a preferredembodiment of the present invention, the nonroad engine is embodied toconstructed in a generator 1 (19.5 KW or less), wherein the exhaustfilter system 2 is adapted for removing substances entrained in anexhaust gas from the generator 1.

Accordingly, the generator 1 can be a nonroad diesel engine type or anonroad gasoline engine type, having a horsepower not more than 25 hp,such as a portable generator or a lawn mower. The generator 1 has anexhaust outlet 11 to discharge the exhaust gas.

The exhaust filter system 2 comprises an outer shelter 20 having an airoutlet 21 and an air inlet 22 adapted for communicatively connectingwith the exhaust outlet 11 of the generator 1, and a filter casing 30,which is supported in the outer shelter 20, having a filter cavity 31communicating the air inlet 22 with the air outlet 21 for guiding theexhaust gas to flow from the air inlet 22 to the air outlet 21 throughthe filter cavity 31.

As shown in FIG. 2, the exhaust filter system further comprises a filtercore 40, which is disposed in the filter cavity 31, comprising aplurality of tubular filtering loops 41 coaxially received in the filtercavity 31, wherein a plurality of air pores 410 are formed on thefiltering loops 41 for allowing the exhaust gas passing therethrough, aplurality of tubular filtering spacers 42 each positioned between eachtwo filtering loops 41 to define a plurality of axial air passages 401between the filtering spacers 42 and the filtering loops 41 so as tocommunicate with the air pores 410 thereof, wherein a plurality of airmeshes 420 are formed on the filtering spacers 42 to communicate withthe air passages 401, and a catalyzing element 43 provided on thefiltering loops 41 and the filtering spacers 42 for chemically reactingwith the substances of the exhaust gas. Thereby, when the exhaust gaspasses through the air passages 401 of the filter core 40, the exhaustgas is evenly diffused to the filter cavity 31 through the air pores 410and the air meshes 420 that increases the contact surface area and thusenhances the chemical reaction of the exhaust gas with the catalyzingelement 43.

According to the preferred embodiment, the outer shelter 20 is made ofheat resistance material, such as steel, rear metals like platinum,palladium and rhodium, transitional metals and lanthanon, wherein theair inlet 22 is embodied as an air conduit having an in-flowing opening221 for connecting with the exhaust outlet 11 of the generator 1 and anelongated out-flowing opening 222 aligned with the filter cavity 31 ofthe filter casing 30 for guiding the exhaust gas from the generator 1 tothe filter cavity 31 through the elongated out-flowing opening 222.Since the exhaust gas is guided to spread out from the elongatedout-flowing opening 222 of the air inlet 22, the exhaust gas can beevenly distributed to the filter core 40 within the filter cavity 31 ofthe filter casing 30, as shown in FIG. 3.

The filter casing 30, having a hollow shape, has an intake opening 32for communicating with the exhaust outlet 11 and a discharging opening33 wherein the filter cavity 31 is communicating the intake opening 32with the discharging opening 33 for guiding the exhaust gas to flow fromthe intake opening 32 to the discharging opening 33 through the filtercavity 31. Accordingly, the exhaust gas is guided to flow from thegenerator 1 to the intake opening 32 through the elongated out-flowingopening 222 of the air inlet 22 of the outer shelter 20 while theexhaust gas is guided to discharged from the air outlet 21 of the outershelter 20 through the discharging opening 33 of the filter casing 30.

As shown in FIG. 2, the filtering loops 41 of the filter core 40 areintegrally extended edge-to-edge in a spiral manner wherein thefiltering loops 41 are formed by coiling up a flat filtering layer 411.The flat filtering layer 411 is constructed as a sheet liked wire nethaving a heat resistance ability wherein the air pores 410 are evenlyformed on the flat filtering layer 4111 for allowing the exhaust gaspassing therethrough.

The filtering spacers 42 of the filter core 40 are integrally extendededge-to-edge in a spiral manner wherein the filtering spacers 42 areformed by coiling up a corrugated filtering layer 421. The corrugatedfiltering layer 421 is constructed as a wire net having a wavy crosssectional and a heat resistance ability, wherein the air meshes 420 areevenly formed on the corrugated filtering layer 421 for allowing theexhaust gas passing therethrough.

In order to form the filter core 40, the corrugated filtering layer 421is overlapped on the flat filtering layer 411 to form an air filteringnet 400 wherein the air filtering net 400 is coiled in a spiral mannerto form the filtering loops 41 and the filtering spacers 42. When theair filtering net 400 is coiled in a spiral manner, the corrugatedfiltering layer 421 functions as a space guider to create a coiled spaceof the flat filtering layer 411 in a coiled manner, as shown in FIG. 4.

Accordingly, the corrugated filtering layer 421 should have a widthshorter than a width of the flat filtering layer 411, wherein when thecorrugated filtering layer 421 is overlapped on the flat filtering layer411, a first longitudinal side edge portion 4111 of the flat filteringlayer 411 is defined to coil as a center of the filter core 40 and asecond longitudinal side edge portion 4112 of the flat filtering layer411 is defined to coil as an outer circumferential loop of the filtercore 40. In other words, the second longitudinal side edge portion 413of the flat filtering layer 411 has a width at least larger than aninner circumference of the filter cavity 31 of the filter casing 30.

The air filtering net 400 in a coiled manner is coaxially disposed inthe filter cavity 31 of the filter casing 30 wherein each of the airpassages 401 is axially extended from the intake opening 32 of thefilter casing 30 to the discharging opening 33 thereof through thefilter cavity 31 in a spiral manner.

An active layer of r-AL2O3 is coated on the flat filtering layer 411 offiltering loops 41 and the corrugated filtering layer 421 of thefiltering spacers 42 as the catalyzing element 43 according to thepreferred embodiment, wherein the catalyzing element 43 is able toremove the harmful substances, such as carbon monoxide, hydrocarbons andnitrogen oxides, from the exhaust gas when the exhaust gas passesthrough the air pores 410 of the flat filtering layer 411 and the airmeshes 420 of the corrugated filtering layer 421.

When the exhaust gas discharges from the generator 1 to the filter core40 through the air inlet 22, the exhaust gas is guided to flow along theair passages 401 and to diffuse to the filter cavity 31 through the airpores 410 and the air meshes 420. Since the flat filtering layer 411 andthe corrugated filtering layer 421 create lots of contacting areasbetween the catalyzing element 43 and the exhaust gas, the catalyzingelement 43 can substantially react with the exhaust gas to remove thesubstances of the exhaust gas.

As shown in FIG. 1, the exhaust filter system 2 further comprises a heatresistance element 50 provided between the outer shelter 20 and thefilter casings 30 for resisting heat distributing from the filter casing30 to the outer shelter 20. Accordingly, the heat resistance element 50is a heat-resisting layer preferably made of asbestos encirclinglycovered on the filter casing 30 so as to prevent the heat conductingfrom the filter casing 30 to the outer shelter 20. It is worth tomention that since the temperature of the exhaust gas from the generator1 is relatively high, the exhaust gas will heat up the filter casing 30when the exhaust gas passes through the filter core 40. Therefore, inorder to prevent the heat conduction of the outer shelter 20 for safetypurpose, the heat resistance element 50 should be enclosed within theouter shelter 20 to resist the heat transferring from the filter core40.

In addition, the heat resistance element 50 can be made of noisereduction material to minimize the noise of the exhaust gas passingthrough the filter core 40, so as to reduce the noise pollution as wellas the air pollution.

Accordingly, the filter core 40 of the present invention provides highsurface-to-volume-ratio reaction surface area, low burning point, shortburning time, anti-vibration, good inverting effect, small exhaustingpressure and no wastage of power.

It is worth to mention that the nonroad compression-ignition engineincorporated with the innovative exhaust filter system of the presentinvention is the first nonroad engine to utilize the exhaust filtersystem as described in the present invention that passes the test andobtains the approval for performance by the United States EnvironmentalProtection Agency, pursuant to Section 213 of the Clean Air Act (42U.S.C. section 7547) and 40 CFR 89. In addition, the nonroad engineincorporated with the exhaust filter system of the present inventionalso obtains certification from the California Air Resources Board,pursuant to the authority vested in the Air Resources Board by Sections43013, 43018, 43101, 43102, 43104 and 43105 of the Health and SafetyCode and pursuant to the authority vested in the undersigned by Sections39515 and 39516 of the Health and Safety Code and Executive OrderG-02-003.

According to the CARB test report for an exhaust filter system 2comprising a filter core 40 having a diameter of 48 mm, a length of 60cm, 50-60 air pores 410 per square centimeter and 200 air meshes 420 persquare centimeter is used to improve the emission of an air-coolednonroad diesel engines.

The following test result is achieved:

Rated Emission Power Standard EXHAUST (G/kW-hr) OPACITY (%) ClassCategory HC NOx NMHC + NOx CO PM ACCEL LUG PEAK kW < 8 Tier 1 STD N/AN/A 10.5 8.0 1.0 N/A N/A N/A CERT — — 6.8 0.002 0.6 — — — STD: StandardCERT: Certification

One skilled in the art will understand that the embodiment of thepresent invention as shown in the drawings and described above isexemplary only and not intended to be limiting.

It will thus be seen that the objects of the present invention have beenfully and effectively accomplished. It embodiments have been shown anddescribed for the purposes of illustrating the functional and structuralprinciples of the present invention and is subject to change withoutdeparture form such principles. Therefore, this invention includes allmodifications encompassed within the spirit and scope of the followingclaims.

1. A process of removing substances entrained in an exhaust gas from anonroad engine having an exhaust outlet to discharge said exhaust gas,comprising the steps of: (a) intaking said exhaust gas from said nonroadengine into a filter cavity containing a filter core therein, whereinsaid filter core has a plurality of air pores distributed; (b) diffusingsaid exhaust gas to said filter cavity through said pores while passingsaid exhaust gas through said filter core; (c) removing predeterminedsubstances in said exhaust gas by chemically reacting said exhaust gaswith a catalyzing element provided around aid air pores of said filtercore to form a filtered exhaust gas; and (d) discharging said filteredexhaust gas from said filter cavity.
 2. The process, as recited in claim1, wherein the step (b) further comprises the steps of: (b-1) guidingsaid exhaust gas to flow through said filter core having a plurality ofair passages in said filter cavity; and (b-2) evenly diffusing saidexhaust gas to said filter cavity through said air pores by passing saidexhaust gas through said air passages of said filter core so as toenhance a chemical reaction of said exhaust gas with said catalyzingelement.
 3. The process, as recited in claim 1, wherein said filtercavity is filled with said filter core.
 4. The process, as recited inclaim 3, wherein each of said air passages is axially extended throughsaid filter cavity in a spiral manner.
 5. The process, as recited inclaim 1, wherein said catalyzing element is coated around said air poresof said filter core.
 6. The process, as recited in claim 1, furthercomprising a step (e) of resisting heat distributing from said filtercavity throughout said process.
 7. The process, as recited in claim 2,further comprising a step (e) of resisting heat distributing from saidfilter cavity throughout said process.
 8. The process, as recited inclaim 5, further comprising a step (e) of resisting heat distributingfrom said filter cavity throughout said process.
 9. The process, asrecited in claim 2, wherein each of said air passages is axiallyextended through said filter cavity in a spiral manner.
 10. The process,as recited in claim 2, wherein said filter core is constructed byoverlapping a corrugated filtering layer having air meshes formedthereon on a flat filtering layer having said air pores formed thereonto form an air filtering net and by coiling said air filtering net toform filtering loops via said flat filtering layer and said filteringspacers via said corrugated filter layer.
 11. The process, as recited inclaim 10, wherein said catalyzing element is coated on said flatfiltering layer and said corrugated filtering layer for chemicallyreacting with said exhaust gas while passing through said air pores andsaid air meshes respectively.
 12. The process, as recited in claim 11,further comprising a step (e) of resisting heat distributing from saidfilter cavity.
 13. An exhaust filter system for a nonroad engine havingan exhaust outlet to discharge an exhaust gas, comprising: a filter bodyhaving an intake, a discharging outlet, and a filter cavity definedbetween said intake and said discharging outlet; a filter core, disposedin said filter cavity, having a plurality of air pores distributed toform a plurality of air passages for allowing said exhaust gas inlettingfrom said intake to flow therethrough to discharge through saiddischarging outlet; and a catalyzing element provided around said airpores and air passages of said filter core for chemically reacting withsaid exhaust gas, wherein said air pores of said filter coresubstantially enhance a chemical reaction of said catalyzing elementwith said exhaust gas which passes through said air passages of saidfilter core and is guided to diffuse to said filter cavity through saidair pores.
 14. The exhaust filter system, as recited in claim 13,wherein said filter core comprises a plurality of tubular filteringloops coaxially received in said filter cavity where said air pores areformed on said filtering loops for allowing said exhaust air passingtherethrough, wherein said filter core further comprises a plurality oftubular filtering spacers each positioned between each said twofiltering loops to define a plurality of axial air passages between saidfiltering spacers and said filtering loops so as to communicate withsaid air pores thereof, wherein a plurality of air meshes are formed onsaid filtering spacers to communicate with said air passages.
 15. Theexhaust filter system, as recited in claim 13, wherein said filtercavity is filled with said filter core.
 16. The exhaust filter system,as recited in claim 14, wherein said filter cavity is filled with saidfilter core.
 17. The exhaust filter system, as recited in claim 13,wherein said catalyzing element is coated around said air pores and saidair passages of said filter body.
 18. The exhaust filter system, asrecited in claim 14, wherein said catalyzing element is coated on saidfiltering loops and said filtering spacers for chemically reacting withsaid exhaust gas while passing through said air pores and said airmeshes respectively.
 19. The exhaust filter system, as recited in claim14, wherein said filter core is constructed by overlapping a corrugatedfiltering layer having said air meshes formed thereon on a flatfiltering layer having said air pores formed thereon to form an airfiltering net and by coiling said air filtering net to form saidfiltering loops via said flat filtering layer and said filtering spacersvia said corrugated filtering layer.
 20. The exhaust filter system, asrecited in claim 19, wherein said corrugated filtering layer has a widthshorter than a width of said flat filtering layer, wherein when saidcorrugated filtering layer is overlapped on said flat filtering layer toform said air filtering net, a first longitudinal side edge portion ofsaid flat filtering layer is defined to coil as a center of said filtercore and a second longitudinal side edge portion of said flat filteringlayer is defined to coil as an outer circumferential loop of said filtercore.